Multi-layered non-woven insulating textile material

ABSTRACT

A multi-layered non-woven hygroscopic fibrous textile material and method of making said material is disclosed. The fibres of the material extend across the thickness of the material and respectively opposite outer layers of fibres are fixed in a matted state relative to the inner fibres. The extent of matting is sufficient to increase thermal insulation per unit thickness relative to the inner fibres, whilst still permitting the outer layer fibres to allow air circulation between and through the outer fibres, to thereby permit moisture retention or release.

It is well known from e.g. U.S. Pat. No. 1,601,625 that the hygroscopicqualities of natural wool can be used in packaging in order to absorbmoisture and/or to thermally insulate the contents, such as by the useof layers of wool fixed to the walls of a cardboard pizza storage cartonas is shown in WO2010/119140. However, as will be appreciated, therelatively bulky nature of wool can take up significant volume withinthe packaging and requires containment in e.g. individual pockets orpillows, one for each wall of the storage carton, which increases thecomplexity of the packaging and is conducive to mass manufacture onlyfor specifically dimensioned and shaped cartons, where the crease linesare between respectively adjacent pockets or pillows of wool.

Packaging of the foregoing type can find use in many industry sectors,such as in the medical field where pharmaceuticals or donor organs arerequired to be transported over relatively long periods, such as 24 to48 hours, but where it is essential to keep the contents of thepackaging within a relatively closely defined thermal range. This may behot, warm, cool or cold, depending upon the contents of the packagingbut where, in each case, the hygroscopic properties of wool are able toassist in providing the necessary insulation and minimising the thermalgradient until delivery of the package.

An obvious problem with packaging which either contains individualpockets or pillows of wool or similar hygroscopic fibres such as juteand cotton is that they limit airflow therebetween or therethrough,thereby adversely affecting the otherwise beneficial hygroscopicproperties of the fibre. Similarly, where e.g. wool is fixed to thewalls of a carton as shown in WO2010/119140 this problem is alsocompounded by the use of a suitable adhesive, which also acts to limitthe ability of the fibres to absorb or release moisture and is notreadily usable where the carton is made of different materials, such asaluminium or plastic.

The present invention is derived from the realisation that there is aneed for a simpler and more effective approach which may be used toinsulate cartons made from all kinds of materials whilst retaining thebenefits of the hygroscopic properties of e.g. wool used as theinsulating medium, although the invention is not limited to the use ofwool.

According to a first aspect of the invention there is provided amulti-layered non-woven hygroscopic fibrous textile material in whichthe fibres extend across the thickness of the material, respectivelyopposite outer layers of fibres being fixed in a matted state relativeto the inner fibres, the extent of matting being sufficient to increasethermal insulation per unit thickness relative to the inner fibres,whilst still permitting the outer layer fibres to allow air circulationbetween and through the outer fibres, to thereby permit moistureretention or release.

With this arrangement the textile material effectively “biomimics” afleece of wool on a sheep, in that the outer layers of the material arematted, corresponding to the matted and hence dense wool immediatelynext to the skin of a sheep and the matted and dense wool on the outsideof the fleece which thereby improves the insulation of the textilematerial without impairing the benefits of the hygroscopic properties ofthe fibres.

Conveniently, the textile material is comprised of fibres which havebeen loose needled felted prior to the respectively opposite outerlayers being matted or compressed so that the inner fibres retain theirrelatively open nature and this may be conveniently assisted by the useof coarse wool fibres where typically the fibres have a thicknessgreater than about 27 microns.

The matting or compression of the respectively opposite outer layers ofthe textile material may conveniently be accomplished byhydroentanglement using respectively opposite water jets, althoughneedle punching, chemical bonding or other methods may instead be usedto compress or matt the respectively opposite outer layers.

Accordingly, a second aspect of the invention extends to a method ofmaking a multi-layered non-woven hygroscopic fibrous textile material inaccordance with the first aspect of the invention including the steps oforientating strands of hygroscopic fibres to form a relatively looselybonded multi-layered fibrous material and thereafter matting orcompressing respectively opposite sides of the material to produce aninsulating textile material.

Conveniently, the method according to the second aspect includes mattingor compressing the respectively opposite outer layers by the use ofhydroentanglement, where the outer fibres of the material are mattedtogether through the use of jets of liquid such as water and thereafterdried. Alternatively, the matting of the respectively opposite outerlayers may be by needle punching or felting, or chemical bonding using asuitably breathable adhesive, such as starch. Other possible methods ofmatting the outer layers are not excluded.

The invention will now be described, by way of example only, withreference to the accompanying drawings in which:

FIG. 1 is a side elevation of a slab of fibrous textile materialaccording to the first aspect of the invention; and

FIG. 2 is a schematic view of a method of making the textile material ofFIG. 1 according to the second aspect of the invention.

Referring firstly to FIG. 1 there is shown an enlarged side view of partof a slab of fibrous textile material shown generally at 1 comprising alightweight inner layer 2 and more dense respectively opposite outerlayers 3, 4, with all three layers having strands of hydroscopic fibresin the form of wool orientated in the same direction. Each of the outerlayers 3, 4 are originally formed from the same relatively lightweightinner material 2 but have been subsequently compressed or mattedtogether to form respectively opposite outer skins surrounding the innerlayer 2 and thereby giving, amongst other things, mechanical strength tothe material 1 so that it may be cut to any desired length or shape forsubsequent use as insulation within e.g. a rigid container such as a boxor between side walls of a container requiring thermal insulation. Thecompression of the respectively opposite outer layers 3, 4 is notcomplete, and is such that it still allows the fibres within thoselayers to absorb or release moisture without acting as a pneumaticbarrier to the less dense inner layer 2. This construction closelymodels or “biomimics” that of a sheep's fleece and it has been foundthat provided the compression or matting of the layers 3, 4 is not toogreat so as to form a thermally conductive barrier the insulation valuesare potentially even better for the less-dense inner layer 2.

The textile material 1 shown in FIG. 1 may be used as it is by being cutinto any required length or shape, or it may be incorporated into oronto other layers of material. For example reflective foils or rigidfoams may be used to assisting insulation and impact absorption etc.

FIG. 2 shows one of several methods that have been used to construct thetextile material of FIG. 1 through the process of hydroentanglementwhere an initially wet but uncompressed moving ribbon of unwoven textilematerial 1 a is compressed by the use of oppositely disposed jet strips5, 6 to reduce the thickness of the outer layers to form the textile 1as shown in FIG. 1. This is achieved by the jet strips 5, 6 beingcomposed of multiple high pressure nozzles spraying fine jets of water(shown arrowed) at a pressure of e.g. 100 bar out of each side of thetextile 1 before it is finally formed and thereafter dried for use. Withthis arrangement, by way of example, an initially 30 mm thick ribbon ofloose needled 800 gsm carded coarse wool was reduced to a finalthickness of 20 mm, with the matted and compressed outer layers eachbeing 4 mm thick. The end result showed significantly improved thermalinsulation performance as compared to the original 30 mm thick ribbon,with a net 10 mm space saving. Hence, by taking a “biomimicry” approachthe invention provides an elegantly simple solution to the generalproblem of providing high performance insulation which, after use, canbiodegrade or be recycled for whatever purpose.

1. A multi-layered non-woven hygroscopic fibrous textile material inwhich the fibres extend across the thickness of the material,respectively opposite outer layers of fibres being fixed in a mattedstate relative to the inner fibres, the extent of matting beingsufficient to increase thermal insulation per unit thickness relative tothe inner fibres, whilst still permitting the outer layer fibres toallow air circulation between and through the outer fibres, to therebypermit moisture retention or release.
 2. A textile material according toclaim 1, wherein the textile material is comprised of fibres which havebeen loose needled felted prior to the respectively opposite outerlayers being matted or compressed so that the inner fibres retain theirrelatively open nature.
 3. A textile material according to claim 1,wherein the matting or compression of the respectively opposite outerlayers of the textile material is accomplished by hydroentanglement. 4.A textile material according to claim 3, wherein the hydroentanglementuses respectively opposite water jets.
 5. A textile material accordingto claim 1, wherein the matting or compression of the respectivelyopposite outer layers of the textile material is accomplished using atleast one of needle punching or chemical bonding.
 6. A method of makinga multi-layered non-woven hygroscopic fibrous textile material accordingto claim 1, the method including the steps of orientating strands ofhygroscopic fibres to form a relatively loosely bonded multi-layeredfibrous material and thereafter matting or compressing respectivelyopposite sides of the material to produce an insulating textilematerial.
 7. A method according to claim 6, further comprising mattingor compressing the respectively opposite outer layers by the use ofhydroentanglement.
 8. A method according to claim 7, further comprisingdrying the material.
 9. A method according to claim 6, furthercomprising matting or compressing the respectively opposite outer layersby the use of at least one of needle punching or chemical bonding.